Wed, Nov

Solar Eclipse Its Occurances & Types


The total or partial concealment of one celestial body by another is called eclipse. Solar eclipse takes place when the light of the sun is totally or partially cut off from.......

By a fortunate coincidence, unique in the solar system, the Moon appears to be the same size as the Sun, so it can completely obscure the Sun when it passes directly between the earth and the Sun. There are three types of solar eclipses: total eclipse, partial eclipse, and annular eclipse. Which of these is seen depends on the position of the earth (and of the observer on Earth) in relation to Moon's shadow. The Moon's orbit is elliptical; hence its apparent size varies as its distance from Earth changes.

Similarly, the apparent size of the Sun varies as a result of the Earth's elliptical orbit. A total eclipse is possible only when the apparent sizes of the Sun and Moon are such that the Moon is large enough to completely obscure the bright disc of the Sun (called the photosphere). But the area of the main shadow cone (the umbra) cast by the Moon is relatively small, so a total eclipse is visible from only limited area of the Earth.

As the Moon orbits the Earth and the Earth rotates on its axis, the umbra passes across the Earth, sweeping out a narrow band (the belt of totality) from which the total eclipse is visible. The length of belt at the maximum is 274 km. On either side of the belt of totality is a second region, from which a partial eclipse can be seen. This area is the zone swept out by the penumbra of the Moon's shadow and is considerably larger than the belt of totality. A partial eclipse can also occur without a total eclipse. This happens when the Sun, Moon, and Earth are not exactly in line, so that only the Moon's penumbra passes across the Earth, the umbra missing our planet entirely.

An annular eclipse occurs when the Earth lies beyond the tip of the Moon's umbra. In this situation, the Moon is too small to completely obscure the Sun's photosphere, which therefore appears as a bright ring around the Moon.

Occurrence of Solar Eclipse:

Solar eclipses are more common than lunar eclipses, there being at least two solar eclipses every year (and sometimes five). There are only 0 to 3 lunar eclipses per year. At a given location however, lunar eclipses are more frequent because every lunar eclipse is visible from the entire hemisphere of the Earth facing the Moon, whereas solar eclipses can be seen from only a very limited area. Solar eclipses can occur only at new moon while lunar eclipses occur only at full Moon. But they don't occur every month' because the Moon's orbit is inclined to the elliptic (the plane of the earth’s orbit).Thus seen from the Earth, the Moon usually passes above or/below the Sun and similarly passes above below the shadow of the Earth.

Lunar Eclipses:

Lunar eclipses occur when the Earth passes directly between the Sun and the Moon. The length of the Earth's umbra shadow cone is more than three times the average distance between the Moon and the Earth, so the shadow is relatively wide at the point where the Moon crosses. As a result, lunar eclipses last for comparatively long time. Three types of lunar eclipses are possible, depending on the orientation of the Moon's orbit relative to the Earth's shadow. A total lunar eclipse occurs when the entire Moon passes through the umbra (it also passes through the penumbra). In a partial eclipse, the entire Moon passes through the penumbra, but only part of it passes through the umbra. And in a penumbra eclipse, the Moon passes through only the penumbra.

Note: The solar eclipses can occur only at new Moon.

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